Java Java.lang.ThreadGroup.enumerate()用法及代碼示例

描述

這個java.lang.ThreadGroup.enumerate(Thread[] list)方法將此線程組及其子組中的每個活動線程複製到指定的數組中。

聲明

以下是聲明java.lang.ThreadGroup.enumerate()方法

public int enumerate(Thread[] list)

參數

list- 這是一個用於放置線程列表的數組。

返回值

此方法返回放入數組的線程數。

異常

SecurityException- 如果當前線程沒有枚舉這個線程組的權限。

示例

下麵的例子展示了 java.lang.ThreadGroup.enumerate() 方法的用法。

package com.tutorialspoint;

import java.lang.*;

public class ThreadGroupDemo implements Runnable {
   public static void main(String[] args) {
      ThreadGroupDemo tg = new ThreadGroupDemo();
      tg.func();
   }

   public void func() {
      try {     
         // create a parent ThreadGroup
         ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");
    
         // create a child ThreadGroup for parent ThreadGroup
         ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");

         // create a thread
         Thread t1 = new Thread(pGroup, this);
         System.out.println("Starting " + t1.getName() + "...");
         t1.start();
            
         // create another thread
         Thread t2 = new Thread(cGroup, this);
         System.out.println("Starting " + t2.getName() + "...");
         t2.start();
            
         // returns the number of threads put into the array
         Thread[] list = new Thread[pGroup.activeCount()];
         int count = pGroup.enumerate(list);
         for (int i = 0; i < count; i++) {
            System.out.println("Thread " + list[i].getName() + " found");
         }

         // block until the other threads finish
         t1.join();
         t2.join();
      } catch (InterruptedException ex) {
         System.out.println(ex.toString());
      }
   }

   // implements run()
   public void run() {

      for(int i = 0; i < 1000; i++) {
         i++;
      }
      System.out.println(Thread.currentThread().getName() + " finished executing.");
   }
}

讓我們編譯並運行上麵的程序，這將產生以下結果 -

Starting Thread-0...
Starting Thread-1...
Thread Thread-0 found
Thread Thread-1 found
Thread-0 finished executing.
Thread-1 finished executing.